Even after hundreds of years, wood framing remains the method of choice for building construction in the United States and many other parts of the world. However, the forest economy has within the past two decades turned from an emphasis on harvesting huge old growth trees to much smaller plantation grown trees. Much of this plantation stock has been grown from genetically improved seedlings selected for rapid growth, high density, and many other desirable heritable characteristics. Along with the change in the nature and size of logs, sawmilling has also evolved into mills that can rapidly process the smaller trees into lumber. Many mills now use chipper-canters which first convert wood along the sides of the logs into pulp chips and leave a cant with parallel sides of a predetermined width. If the log was sufficiently large, side boards may be taken off the initial cant leaving a center cant to be cut into additional boards, usually in an automated gang saw. Scanners are widely used to measure the logs and set the saws to determine the breakdown pattern. Larger logs will yield side boards and a center cant. In order to maximize yield, wane will often be allowed along the corners of some pieces. Wane results from the piece not entirely fitting into a prescribed cross sectional rectangle for all or part of its length so that some of the original surface adjacent to the bark remains along one or more edges. Grading rules permit minor wane for most lumber grades but excessive wane is cause for downgrading or rejection of an individual piece.
Wane and other edge defects on lumber are particularly annoying to builders. Wall studs may be taken as an example. These have other materials nailed to them including sheathing and siding on the exterior and gypsum drywall on the interior. For ease of nailing and solidity of construction a sound, full width flat surface is desirable.
Coniferous trees have a core portion of juvenile wood about 10-15 growth rings wide. This core wood is known to be less dense and generally weaker than wood formed later during the trees growth. It is inherent that lumber having wane will have come from the outside portion of the log from which it was cut and will generally be of higher strength and stiffness than that cut from the core portion of the log. If the trees have been pruned during their growth, lumber from the outside will also usually have a lower amount of defects such as knots. For these reasons it is desirable to convert this wood into the highest value product possible. Removing any wane without substantial loss in yield would be a major step in increasing lumber value since the affected lumber generally has prime structural characteristics.
The present invention offers a solution to the problems caused by wane and presents a premium product that is wane free and full sized. The product can be made by upgrading pieces having moderate wane without loss in lumber dimensions.